Curious if I should bring this up? Possible safety concern at my preschool.

So I am a Pre-K teacher at a preschool and daycare. I work with the 3’s. The front door to the building cannot be unlocked without a key fob. I was in my classroom with my kids around pick up time when the back door which leads to the playground opened, and a middle aged man in a long trench coat walked into the class. I asked who he was and the lead teacher told him, “your kid is not in this class.” Then he walked through the classroom instead of going back to the play area, and entered the hallway without saying anything to us. It totally skeeved me out. If you need a key fob to get in through the front door, why are the back doors always unlocked? Evacuation protocol? Idk, should I bring this up? Even parents can be unsafe. Edit: I spoke to one of the managers and the back doors are not locked during daytime because the gates are locked… the only room without a gate is the infants room and that is locked at all times. Apparently.